The invention relates to an adjustable steering column for a motor vehicle, comprising a jacket unit rotatably supporting a steering spindle, first and second side jaws that can be stationarily secured in position on the vehicle body and between which the jacket unit is disposed, a securement device in the open state of which the jacket unit can be adjusted such that it is adjustable with respect to the side jaws in at least one adjustment direction and, in the closed state of which, the set position of the jacket unit is secured in position with respect to the side jaws. The steering column further comprises a clamp bolt penetrating the side jaws through openings, the clamp bolt being shiftable in its axial direction during the opening and closing of the securement, and first and second securement elements between which the jacket unit is disposed and of which the first securement element in the closed state of the securement device cooperates with a first counter-securement element disposed on the first side jaw or is retained by it or is disposed on an intermediate unit disposed between the jacket unit and the side jaws or is retained by it, and of which the second securement element in the closed state of the securement device cooperates with a second counter-securement element disposed on the second side jaw or retained by it or is disposed on the intermediate unit or is retained by it.
In such steering columns, a clamp bolt penetrates side jaws secured in position on the side of the vehicle body, between which the jacket unit supporting the steering spindle is disposed. On both sides of the side jaws, securement elements are provided for the securement of the set position of the steering column in the closed state of the securement device. These types of steering columns are known in various embodiments and are widely utilized. Through the clamp bolt penetrating the two side jaws and the securement elements located on both sides of the side jaws can be achieved a compact and stable implementation in which the load transfer into the vehicle body takes place as uniformly as possible.
The securement of the at least one adjustment capability of the steering column in the closed state of the securement device can herein be attained through elements acting under form closure or elements acting under force closure or by elements acting under force closure as well as also form closure or through combinations thereof, wherein these elements encompass the securement elements and counter-securement elements. The steering column can be adjustable in its longitudinal direction or in its height or inclination direction as well as also in length as well as also in height or inclination.
Such steering columns are disclosed for example in DE 10 2007 003 091 B3, WO 2007/009576 A1, WO 2008/011945 A1 and EP802 104 A1. For example, WO 2007/009576 A1 discloses an adjustable steering column in which the securement elements disposed on the clamp bolt on both sides of the side jaws cooperate with at least on one of the two sides of the jacket unit with a counter-securement element which, in the unstressed state includes a slicing, projecting resiliently from the surface of the counter-securement element. Through this slicing an additional retention force against a dislocation, in particular in the event of a crash, of the steering column can be applied through the form-closure cooperation with the securement element. For the stand-off of the securement element from the counter-securement element in the opened state of the securement device, herein at least one spring element is provided which acts between the securement element and the counter-securement element. In the device disclosed in DE 10 2007 003 091 B3 at least one of the securement elements is formed by a lamella which includes toothings on its edges oriented in the direction of the height adjustment. In the closed state of the securement device, the securement element is pressed onto the side jaw against the force of spring arms which, in the opened state of the securement device, keep the securement element spaced apart from the side jaw, wherein the toothings of the securement element come into engagement with toothings of the side jaw in order to block the height displacement. In the case of the steering columns disclosed in WO 2008/011945 A1 and EP 802 104 A1 the securement of the adjustability of the steering column in the closed state of the securement device takes place only through elements cooperating through friction closure. In the latter case, intersecting spring packs disposed on both sides of the side jaws are provided in order to increase the clamping forces in the closed state of the securement device.
DE 102 34 514 B3 further shows a steering column with a securement device in which toothings are disposed or held on one side on the jacket unit and on the side jaw, which extend, for one, in the direction of the length adjustment, for another, in the direction of the height or inclination adjustment and which, in the closed state of the securement device cooperate with toothings of parts disposed on the clamp bolt. To enable the two adjustment directions to be latched and unlatched simultaneously, the separation distance of the two parts comprising the toothings must be precisely adapted. In the opened state of the securement device, the toothings of the parts disposed on the clamp bolt are brought out of engagement with the toothings of the jacket unit or the side jaw through a spring also disposed on the clamp bolt. A similar adjustable steering column is also disclosed in DE 10 2006 016 361 B3, wherein here the toothings acting in the two adjustment directions are implemented on a single securement part disposed on the clamp bolt.
Apart from such securement devices, in which on both sides of the jacket unit side jaws are provided penetrated by the clamp bolt, still further steering columns with securement devices are also known, in which only on one side of the jacket unit a side jaw is disposed onto which the jacket unit is pressed in the closed state of the securement device. The clamp bolt projects hereby through the side jaw into the jacket unit. Such securement devices are disclosed, for example, in EP 0 836 981 B1 and DE 10 031 721 C1. In these embodiments a massive and more complex guidance of the jacket unit is required in order to obtain adequate stability and to counteract tilting or canting.